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forthcoming from the expectations of his older readers, who remembered the actual reasonings of Protagoras and required of Plato an attempt to meet them?
And the philosopher must urge this difficulty still more insistently than the literary critic. The Theætetus contains a position of immense philosophic importance, whether it originated with Protagoras or with Plato. It is never dealt with. Why not? And is not the philosopher seriously concerned to estimate how much it detracts from the security of Plato’s chosen creed to have left a hostile stronghold, however weakly garrisoned, untaken, nay unassailed, in his rear?
(6) When after a long digression, in the course of which Plato emphasizes the hopeless transcendence of the truly real and valuable with the utmost acerbity, the argument is resumed in 177 C, Plato first, quite superfluously, proves what the Protagoras of the Speech had long ago pointed out, viz., that cities often do not know their own advantage.
(7) In 178 A a fresh point is made. Can it be maintained that each man is the measure not only of his present perception, but also of the future? Will that be exactly as he anticipates? And does not the knowledge of the advantageous depend mainly on the future?
The Platonic ‘Socrates’ appears finally to rest his case on this point and on the argument in 171 C [our No. (4)], by which Protagoras was alleged to refute himself. In reality, however, the appeal to the future leads to a triumphant vindication of the Humanist interpretation. For how does the future decide between two rival theories of truth? By the value of the consequences to which they severally lead. That is precisely the meaning of the pragmatic testing of truth by its consequences. Whether Protagoras would have replied in this way if the point had been brought to his notice, we are not, of course, in a position to say; but enough has probably been said to show that if we read the Theætetus critically and do not credulously swallow every claim Plato chooses to make without verifying it, there can be no question of a refutation of the argument of the Protagoras Speech by the subsequent criticism.
